Legal Question in Real Estate Law in Washington

This type of situation happens often and it comes down to a question of reasonableness and probabilities. In other words, how reasonable is your neighbor's demand, and what are the probabilities that any harm will occur to property or people?

You should decide how much you care about keeping this tree and what it will cost to remove it. If it is really not a big deal to you, and considering how much it would cost you if it fell down as your neighbor has now put you on notice that it could, then I say get rid of the tree and protect yourself. Maybe you can even negotiate with your neighbors to have them pay part of the removal fees since it is done in part for their benefit.

On the other hand, if you really value the tree or have other reasons to try and avoid cutting it down, then perhaps you should hire your own arborist, have them inspect the tree and issue a written report addressing your neighbor's concerns. You will practically be required to do whatever the arborist suggests, otherwise, if you don't and something happens, then you will have no place to hide. You will have been put on notice of the dangers by both your neighbor and your arborist.

If the tree falls, and your neighbor has put you on notice with a certified letter of the danger, then you are going to be liable. Your insurance company is likely to deny the claim unless you give them a copy of the letter (sent by you to the insurance company by certified mail also) on the basis that you were aware of a particular risk and purposely hid that information from them.

As for how fast you should act, that is also a variable question. My answer is, act before the next storm to reduce your risks. Whether it is necessary to cut down the tree will be based on whether you can neutralize the problem without cutting it down. For example, can you trim enough branches so the tree can survive yet not be unstable or a risk to fall over in a storm?

Before you respond to your neighbor, my suggestion is that you consult a local attorney, have them read the neighbors' letter, and perhaps decide if they ought to respond on your behalf to protect your interests.

I hope this helps and best of luck to you.